Which methane correction factor should a labour colony or company township use for pit latrines, septic tanks or a sewer in the Intergovernmental Panel on Climate Change method?

In the Intergovernmental Panel on Climate Change (IPCC) 2006 domestic wastewater table, the methane correction factor (MCF) is 0.5 for a septic system, 0.7 for a latrine in a wet climate with a high water table, 0.1 for a dry-climate family latrine and 0 for a flowing sewer. Each scales 0.6 kilograms of methane per kilogram of biochemical oxygen demand.

Table 6.3: factor by system (range)

• Septic system: 0.5 (0.5). The table says half of the biochemical oxygen demand (BOD) settles in the anaerobic tank.
• Latrine, dry climate, water table lower than the latrine, small family of 3 to 5 people: 0.1 (0.05 to 0.15). Same, communal with many users: 0.5 (0.4 to 0.6). Wet climate or flush water use, water table higher than the latrine: 0.7 (0.7 to 1.0). Latrine with regular sediment removal for fertiliser: 0.1 (0.1).
• Sewer: stagnant, open and warm 0.5 (0.4 to 0.8); fast moving and clean, open or closed, 0 (0). River, lake or sea discharge 0.1 (0 to 0.2).
• Centralised plants: aerobic and well managed 0 (0 to 0.1); aerobic but overloaded or not well managed 0.3 (0.2 to 0.4); anaerobic digester for sludge or anaerobic reactor 0.8 (0.8 to 1.0); shallow anaerobic lagoon under 2 metres 0.2 (0 to 0.3); deep lagoon over 2 metres 0.8 (0.8 to 1.0). Methane recovery is not considered in the digester and reactor rows.

The sum behind it

Equation 6.3 multiplies the number of people, the BOD per person per day in grams, 0.001, a correction factor I and 365 to give kilograms of BOD a year. For India the guide's BOD figure is 34 grams per person per day, with a range of 27 to 41. I is 1.25 for wastewater that is collected, to allow for industry and shops discharging into the same sewers, and 1.00 for wastewater that is not collected.

The emission factor for each system is 0.6 kilograms of methane (CH4) per kilogram of BOD times the table's factor (Equation 6.2; on a chemical oxygen demand basis the figure is 0.25). Equation 6.1 then multiplies the factor by the BOD, less any removed as sludge, less any CH4 recovered. With several systems, it weights each system's factor by the share of people using it, by income group (the guide's U times T).

Which factor is yours

The table sorts latrines by climate and water table, which are site facts you have to judge and write down. A pit latrine at a camp in a high rainfall area with a high water table is the 0.7 row. The guide's phrase for the dry rows is 'dry climate', and it does not define it in numbers, so state what you assumed.

If you own and run these systems, the methane is in your Scope 1, as on the septic tank page. Our reading: workers housed in a colony run by someone else are outside your boundary.

A labour colony with 500 residents, all day, uncollected wastewater (example quantities)

• BOD: 500 x 34 x 0.001 x 1.00 x 365 = 6,205 kilograms a year
• Wet-climate latrine, 0.7: 6,205 x 0.6 x 0.7 = 2,606 kilograms of CH4
• Septic tank or communal dry-climate latrine, 0.5: 6,205 x 0.6 x 0.5 = 1,862 kilograms
• Family latrine in a dry climate, 0.1: 6,205 x 0.6 x 0.1 = 372 kilograms. Flowing sewer to a well-managed aerobic plant, 0: none
• At an example global warming potential (GWP) of 28, in tonnes of carbon dioxide equivalent: 73.0, 52.1 and 10.4

The 500 residents and the GWP are example values. 34 grams of BOD per person per day is the guide's value for India. Residents at the colony for the whole day are assumed, so no part-day share is taken.

What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records, so power for your sewage pumps and treatment plant shows up once uploaded. Head counts and the type of each latrine or tank come from your camp records, which you add.

• Septic tank methane in Scope 1
• Aerobic sewage plant: methane and nitrous oxide
• Sewage plant power per kilolitre
• Free calculators

Sources: IPCC 2006 Guidelines, Volume 5 chapter 6: Wastewater Treatment and Discharge (Equations 6.1 to 6.3, Tables 6.2 to 6.4)

Last reviewed 2026-11-05. Defaults are from the 2006 IPCC Guidelines and rest on expert judgement by the chapter authors. Confirm with your verifier which system row and climate you use for each block.